A brand-new development in the search for a new hampshire teenager missing for more than two months. A new lead. A mysterious letter from the girl to her parent. Linsey davis is tracking the story. Reporter: We spoke exclusively with abbey hernandez's mother last night. She never gave up home. This letter gave her an norls amount of hope. She says he sees abbey in her dreams and doesn't want to wake up because that's when this nightmare returns. It's been two months since the hernandez family has seen their youngest daughter, 15-year-old abgail. We're concerned for her safety. She has somebody helping her whether that be a friend or what we fear is a foe. Reporter: The case was initially considered a runaway. But took a turn when the mother received a letter from abigail ON NOVEMBER 6th. Authorities are not releasing details about it. They believe she is in grave danger. One fbi special agent saying it could be a situation like the young women tortured and he would captive. I want to see you again. Reporter: In her first interview, zenya hernandez says she has new hope that her daughter is alive. It was numbing for the first three weeks. Four weeks. And then, I received the letter. It was like exhilarating. I wept from constantly thinking what could have happened and going through every theory and case scenario in my head, like nonstop. To like, okay, there's hope. Reporter: The fbi is hoping for another communication from abigail. I'm playi praying a miracle happens. Reporter: This is the last nope photo of abby. The day she vanished. A lot of people say I'm living the worst thing I parent can live through. It is very hard. But I'm relieved every day that we don't have bad news. Reporter: Abby's mother says the best way for her to cope is to keep searching. I'll never stop looking. I'll never lose hope. Reporter: According to the fbi, the letter has not produced ANY VIABLE LEADS As TO ABBY'S Whereabouts. They have not released information about the letter because they fear copy cats. If abby is listening, they want her to know they haven't given up on her case.

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